1. Technical Field
The present disclosure relates to a rolling bearing device including an oil supply unit that supplies minute amounts of lubricating oil to the bearing part.
2. Description of Related Art
Rolling bearings are used, for example, as main shaft bearings of machine tools, and some bearings employ oil-air lubrication to secure the lubricity. In the case of oil-air lubrication, however, air consumption pushes up the running cost. The required ancillary equipment, including an oil-air supply device and an air cleaning unit, may also push up the equipment cost.
A bearing device is known that has a built-in oil supply unit as alternative means for supplying oil to the rolling bearing (e.g., see Japanese Patent Application Publication No. 2004-108388). In this bearing device, the oil supply unit is mounted on the outer ring, and the rolling bearing and the oil supply unit are integrated. The oil supply unit includes a pump that discharges lubricating oil to an annular space formed between the inner ring and the outer ring.
The lubricating oil is discharged from the pump in minute amounts, and the amount of lubricating oil to be discharged is adjusted by controlling the action of the pump. The lubricating oil is discharged by the pump intermittently (at time intervals) as oil droplets, with the amount of lubricating oil discharged from the pump by one action being, for example, about several picoliters to several hundred nanoliters. According to this bearing device that includes the oil supply unit along with the rolling bearing, minute amounts of lubricating oil can be discharged to the annular space between the inner ring and the outer ring, and the rolling bearing is lubricated as the discharged lubricating oil adheres to the raceway surfaces of the inner ring and the outer ring, the rolling elements, and the cage retaining the rolling elements.